.NET Core Introduction & History

.NET Core (now simply .NET from version 5 onwards) is Microsoft's modern, open-source, cross-platform successor to the original .NET Framework. It represents one of the most significant architectural decisions in enterprise software development of the past decade — Microsoft reimagined their flagship development platform from the ground up to run on Windows, Linux, and macOS, to be modular and lightweight, and to be fully open-source under the MIT license on GitHub. This decision transformed .NET from a Windows-only enterprise platform into a competitive, community-driven framework capable of powering everything from microservices on Linux containers to high-performance web APIs serving millions of requests per second. The history of .NET Core began with .NET Framework, released in 2002. .NET Framework was a powerful but monolithic, Windows-exclusive runtime. As cloud computing and containerization grew in importance, its inability to run on Linux and its tightly coupled, large footprint became significant disadvantages. In 2016, Microsoft released .NET Core 1.0 — a complete rewrite designed from scratch to be lightweight, fast, and cross-platform. The framework evolved rapidly: .NET Core 2.0 (2017) added broad API compatibility, .NET Core 3.0 (2019) added desktop application support, and .NET 5 (2020) unified the entire .NET ecosystem into a single platform. Today, .NET 8 (the current Long Term Support release) is the standard for new enterprise development. It delivers performance that benchmarks among the fastest web frameworks in any language, with ASP.NET Core consistently ranking in the TechEmpower Framework Benchmarks. The runtime includes Ahead-of-Time (AOT) compilation via Native AOT for near-instant startup times, making it suitable for serverless functions and containers. The C# language has evolved alongside the runtime, with modern features like nullable reference types, records, pattern matching, and async streams making code more expressive and safer. For developers entering the industry today, .NET Core proficiency is highly marketable. Microsoft Azure is the second-largest cloud platform in the world, and .NET powers a significant portion of enterprise applications hosted on Azure. Companies including Samsung, Stack Overflow, Siemens, KPMG, and thousands of enterprises across banking, healthcare, logistics, and e-commerce run their critical systems on .NET. This module establishes the foundational knowledge you need to begin building with this powerful, professional-grade platform.

.NET Core is a free, open-source, cross-platform framework for building modern applications. It's a redesign of .NET Framework that runs on Windows, macOS, and Linux, providing a unified development experience across platforms.

**Key Differences:** **Platform Support:** - .NET Core: Cross-platform (Windows, macOS, Linux) - .NET Framework: Windows-only **Deployment:** - .NET Core: Self-contained deployments, framework-dependent deployments - .NET Framework: Requires framework installation **Performance:** - .NET Core: Optimized for performance and memory usage - .NET Framework: Legacy performance characteristics **API Surface:** - .NET Core: Streamlined, modern APIs - .NET Framework: Larger, legacy API surface **Development:** - .NET Core: Modern tooling, CLI-first approach - .NET Framework: Visual Studio-centric development